SCIENCE 



New Series 

 Vol. LII, No. 1355 



Friday, December 17, 1920 



Single Copies, 15 Cts. 

 Annual Scbsceiption, $6.00 



The Visual Appeal 



is stronger than that of the spoken 

 word. But combine the two in audi- 

 torium, classroom or laboratory and you create ; 

 indelibly stamp themselves in the minds of yoi 



sions that 

 ers.; 



/ 



Appreciation of this truism in education is responsible for an 

 increasing installation of the / 



BAUSCH 8C LOMB BALOPTICON 



The Perfect Stereopticon 



in various institutions of learning. Models are made for 

 showing either lantern slides or opaque objects, or both — 

 photo prints, postcards, specimens, maps, illustrations, etc. 



Bausch ^ Ipmb Optical Q. 



DEC? 



552 ST. PAUL STREET 



ROCHESTER, N. Y. 



Leading American Makers of Photographic Lenses, Microscopes, Projection-Apparatus 

 (Balopticons), Ophthalmic-Lenses and Instruments, Phoiomicrographic Apparatus, Range 

 Finders and Gun Sights for Army and Navy, Searchlight Reflectors, Stereo-Prism 

 Binoculars, Magnifiers, and other high-grade Optical Products 



